For instance, these are the "combined" fuel economy numbers for numerous similar vehicles in Australia (all numbers converted from l/100km from GreenVehicleGuide):

Car

Engine

US MPG

L/100km

km/L

Toyota Prius C

1.5L

60

3.9

25.6

Smart ForTwo (with auto Start/Stop)

1.0L

53

4.4

22.7

Mitsubishi Mirage (no Start/Stop)

1.2L

51 - 48

4.6 - 4.9

21.7 - 20.4

Chevrolet Spark / Holden BarinaSpark

1.2L

45 - 41

5.2 - 5.8

19.2 - 17.2

Kia Rio

1.6L

42 - 39

5.6 - 6.1

17.9 - 16.4

Toyota Yaris

1.5L

41 - 35

5.7 - 6.7

17.5 - 14.9

Ford Fiesta

1.6L

39

6.1

16.4

Hyundai Accent

1.6L

39 - 37

6.0 - 6.4

16.7 - 15.6

Honda Fit

1.5L

37 - 35

6.4 - 6.7

15.6 - 14.9

According to the Australian mileage testing, only the Smart ForTwo (with start/stop) and Prius C (a hybrid) beat the Mirage out in fuel economy. That is a heck of a good start.

Sadly, the Australians don't get the Scion/Toyota iQ which currently holds the Canadian and U.S. title for having the best combined fuel economy rating for a non-hybrid (EPA: 37 mpg US combined). So we don't know yet for sure if Mirage will wear the MPG crown in the North America.